Terpolymer pour point depressant

ABSTRACT

A TERPOLYMER OF 30-85 WT. PERCENT ETHYLENE, 10-40 WT. PERCENT OF AN OLEFINICALLY UNSATURATED C3 TO C5 ESTER, AND 5-30 WT. PERCENT OF AN ESTER OF ETHYLENEDICARBOXYLIC ACID AND A C1 TO C24 MONOHYDRIC ALCOHOL HAVING A 1000 TO 4000 MOLECULAR WEIGHT IS USEFUL AS A POUR DEPRESSANT FOR DISTILLATE FUELS. THE TERPOLYMER CAN BE PREPARED BY POLYMERIZING THE MONOMERS AT 500 TO 1500 P.S.I. AT 250* TO 350*F. FOR 3 TO 24 HOURS USING A PEROXIDE CATALYST.

United States Patent 3,565,947 TERPOLYMER POUR POINT DEPRESSANT StephanIlnyckyj, Islington, Ontario, Canada, assignor to Esso Research andEngineering Company, a corporation of Delaware Application Mar. 11,1966, Ser. No. 542,981, now Patent No. 3,341,309, which is acontinuation-in-part of application Ser. No. 297,036, July 23, 1963.Divided and this application Apr. 21, 1967, Ser. No. 634,421

Int. Cl. C07c 69/60 U.S. Cl. 260-485 Claims ABSTRACT OF THE DISCLOSURE Aterpolymer of 30-85 wt. percent ethylene, 1040 wt. percent of anolefinically unsaturated C to C ester, and 5-30 wt. percent of an esterof ethylenedicarboxylic acid and a C to C monohydric alcohol having a1000 to 4000 molecular weight is useful as a pour depressant fordistillate fuels. The terpolymer can be prepared by polymerizing themonomers at 500 to 1500 p.s.i. at 250 to 350 F. for 3 to 24 hours usinga peroxide catalyst.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a divisionof Ser. No. 542,981 filed Mar. 11, 1966 now U.S. 3,341,309; which inturn was a continuation-in-part of Ser. No. 297,036 filed July 23, 1963which is now abandoned.

DESCRIPTION OF THE INVENTION The present invention is concerned with animproved terpolymer pour point depressant and with its method ofmanufacture. The terpolymer of the present invention is particularlyeffective for use with middle distillates. The pour depressant of thepresent invention comprises a terpolymer of ethylene, an alkyl fumarateor maleate and an olefinically unsaturated aliphatic ester containingfrom about 3 to 5 carbon atoms per molecule. The terpolymers ofdesirable molecular weights are obtained by controlling the conditionsof the reaction. A particularly preferred terpolymer of the presentinvention is a terpolymer of ethylene, vinyl acetate and dilaurylfumarate.

With the increase in the use of hydrocarbon fuels of all kinds, seriousproblems have arisen in areas frequently subjected to low temperaturesin the cold test characteristics of fuels. Particularly serious problemshave been encountered with heating oils and diesel and jet fuels thathave too high a pour point, resulting either in distributiona1 oroperating difficulties or both. For example, the distribution of heatingoils by pumping or syphoning is rendered diflicult or impossible attemperatures around or below the pour point of the oil. Furthermore, theflow of the oil at such temperatures through the filters is notmaintained, leading to equipment failures.

Also, the low temperature properties of petroleum distillate fuelsboiling in the range between about 250 and about 750 F. have attractedincreasing attention in recent years because of the growth of market forsuch fuels in subarctic areas and because of the development "ice ofturbo-jet aircraft capable of operating at altitudes where temperaturesof -50 F. or lower are encountered.

It is, therefore, an object of the present invention to utilize animproved terpolymer and describe its method of manufacture. Theseterpolymers are particularly effective pour depressants for middledistillates and lighter oils. In general, these oils boil in the rangefrom about 250 and 750 F.

It is a still further object of the present invention to provide heatingoils, diesel fuel oils, kerosenes and jet fuels having low pour points.Aviation turbo-jet fuels in which the polymers may be used normally boilbetween about 250 and about 550 F. and are used in both military andcivilian aircraft. Such fuels are more fully defined in U.S. MilitarySpecifications MIL-F-5624C, MIL-F25 5 54A, MILF25 558A, and amendmentsthereto. Kerosenes and heating oils will normally have boiling rangesbetween about 300 and about 750 F. and are more fully described in ASTMSpecification D39648T and supplements thereto, where they are referredto as No. 1 and No. 2 fuel oils. Diesel fuels in which the polymers maybe employed are described in detail in ASTM Specification D97553T andlater versions of the same specification.

In accordance with the present invention the use of ethylene monomer inthe propagation reaction for pre paring the terpolymers herein iscritical. The amount of ethylene present in the polymer should vary inthe range from about 30-85 wt. percent, preferably from about 55-70 wt.percent, as for example 50 wt. percent.

Esters of ethylenedicarboxylic acid employed as the second constituentof the terpolymers are alkyl esters of fumaric and maleic acids havingesterifying groups containing from 1 to about 24 carbon atoms. Alkylesters in which the alkyl groups contain from about 4 to about 18 carbonatoms are particularly useful because of the solubility properties whichthey impart to the terpolymers, and are therefore preferred for thepurposes of the invention. In addition, the esters may be mono ordialkyl esters, but it is preferred, however, that they be dialkylesters. The amount of fumarate or maleate present in the terpolymershould be in the range of from about 5-30 wt. percent, preferably fromabout 10-20 wt. percent as, for example, 15 Wt. percent. Examples ofsuch esters which may be employed to prepare the terpolymers includedibutyl fumarate, di-n-hexyl fumarate, dilauryl maleate, dilaurylfumarate, monohexadecyl fumarate, dioctadecyl maleate, di-Z-ethyl-hexylmaleate, distearyl fumarate, dicetyl fumarate and the like.

Esters of fumaric or maleic acids prepared from commercial mixedalcohols may also be used in preparing the terpolymers employed inaccordance with the invention. Such mixed alcohols include thoseprepared by the hydrogenation of coconut oil and marketed commerciallyunder the trade name Lorol. One such mixture of alcohols consistsprimarily of lauryl alcohols but contains compounds of from about 10 toabout 18 carbon atoms per molecule. This particular Lorol alcoholnormally contains about 4.0% of C alcohol, about 55.5% of C alcohol,about 22.5% of C alcohol, about 14.0% of C alcohol, and about 4.0% of Calcohol. Tallow alcohol is a similar mixed product consisting primarilyof cetyl and stearyl alcohols derived from tallow fat by saponification."Other mixed alcohols available commercially are derived from soybeanoil, cotton seed oil, and similar natural products and also have chainlengths within the range recited above which render them suitable forpurposes of the invention.

A still further class of alcohols which may be employed in preparing theesters used as monomers in accordance with the inventions are the oxoalcohols which are derived by the oxonation and hydrogenation ofolefins. A variety of alcohols may be produced by this method, dependingupon the particular olefins employed. If a C olefin derived frompropylene and butylene is used, for example, C oxo alcohol is produced,Typically, C oxo alcohol consists of 29% of 3,5-dimethyl hexanol, 25 of4,5-dimethyl hexanol, 17% of 3,4-dimethyl hexanol, 16% of4-methylheptanol and S-methyl heptanol, 2.3% of 4-ethyl hexanol, 1.4% of5,5-dimethyl hexanol, 4.3% of 2-alkyl-alkynols, and of other alcohols.If a propylene tetramer is subjected to oxonation and subsequenthydrogenation, a C oxo alcohol is produced. This higher alcohol alsoconsists of a mixture of alcohols similar to the C oxo alcohol mixture.Other alcohols of different chain lengths and different degrees ofbranching may be produced in an analogous manner. All of these alcoholsare suitable for use in forming the esters employed as one of themonomers of the additives of the invention.

The third monomer which is useful for polymerization with theaforedescribed monomers includes the olefinically unsaturated aliphaticesters containing from about 3 to 5 carbon atoms per molecule. Ingeneral, these compounds may comprise vinyl acetate, vinyl propionate,methyl methacrylate, and the like. The amount of C -C unsaturated esterpresent in the terpolymer is within the range between about to 40 wt.percent, preferably from about -30 Wt. percent as, for example, wt.percent.

The molecular weight of the terpolymer is critical and should be in therange from about 1,000 to 4,000, preferably in the range from 1,500 to3,000, such as about 2,500. The molecular weights are determined inphenanthrene by K. Rasts method (Ber. 55, 1051,3727 (1922) Theterpolymer as described above is used in a concentration in the rangefrom about .001 to 0.09% by weight, preferably in a concentration in therange from about 0.01 to 0.05% by weight.

The polymerization process employed to produce the terpolymer of thepresent invention is conducted in a typical hydrocarbon polymerizationsolvent as, for example, hexane, cyclohexane, n-heptane, isobutylalcohol and the like. It is preferred, however, to use a benzenesolvent.

The initiator comprises any conventional peroxide type catalyst such asbenzoyl peroxide, tert.-butyl hydroperoxide, di-tert.-butyl peroxide,cumene peroxide and the like. Di-tert.-butyl peroxide in varying amounts(e.g., 0.012.0 wt. percent based on reactants) Was found to beparticularly effective in promoting the polymerization.

The temperature of the polymerization reaction is in the range fromabout 250 to 350 F., preferably from 275 to 325 F. A very desirabletemperature is about 300 F. The pressure is in the range from about 500to 1,500 pounds, preferably 800 or 900 pounds.

For example, the autoclave or similar equipment containing the solvent,initiator, dilauryl fumarate and vinyl acetate is purged with nitrogen,then with ethylene before charging with a sufficient amount of ethyleneto yield the desired pressure when heated to the reaction temperature.During the polymerization, additional ethylene is added to maintain thepressure at the desired level. The polymerization time may vary widely,e.g., from about 1 to about hours. Polymerization is considered completewhen the pressure drops less than 50 p.s.i.g. per hour. The product isstripped free of solvent, dilauryl fumarate and unreacted vinyl acetateunder vacuum.

The present invention may be more fully understood by reference to thedrawing illustrating one embodiment of the same. Referring specificallyto the drawing, reactor 1 is first purged with nitrogen, introduced bymeans of line 2 and pump 3. Reactor 1 is then purged with ethylene whichis introduced by means of line 2 and pump 3. Gases are removed fromreactor 1 by means of line 4. The reactor is maintained at a positivepressure in the range from about 50 to pounds absolute.

Approximately 1,400 parts by volume of benzene is introduced intoreactor 1 from benzene storage 5 by means of line 6 and pump 7. Reactor1 is then raised to a temperature of about 300 F. by means of heatingelement 8 wherein a heating fluid or equivalent means is introduced bymeans of line 9 and withdrawn by means of line 10. Reactor 1 is held atabout 300 F. during the course of the reaction by the removal of heat orby the addition of heat thereto by suitable means. Ethylene isintroduced by means of line 2 so as to raise the pressure of the reactorto about 900 pounds per square inch absolute.

The addition of vinyl acetate, dilauryl fumarate, and ofdi-tertiary-butyl-peroxide is started concurrently. It is also possibleto stage the addition of the two esters in either order. The mixture ofvinyl acetate and dilauryl fumarate is Withdrawn from storage zone 11and introduced into the reactor by means of line 12 and pump 13.Approximately 215 parts by volume of vinyl acetate mixed with forexample parts by volume of dilauryl fumarate are added over a four hourperiod. The peroxide is introduced by passing benzene into storage zone14 by means of line 15 and then introducing the solution into thereactor 1 by means of line 16 and pump 17. Approximately 15 parts byvolume of peroxide are combined with 45 parts by volume of benzene. Theresulting 60 parts by volume of 25% peroxide solution in benzene isadded to reactor 1 over a three to live hour period.

After the addition of the peroxide has been completed, the reactor isheld for an additional one to two hours at a temperature of about 300 F.The ethylene is added continuously so as to maintain the pressure atabout 900 pounds.

At the end of the reaction, the reactor is allowed to cool to about F.and the reaction product is with drawn by means of line 19 and passedinto separation zone 20. Excess ethylene is removed overhead fromseparation zone 20 by means of line 21. The polymer product comprisingthe terpolymer in a benzene solution may be withdrawn by means of line22 and further handled as desired. Under certain instances, it may bedesirable to separate at least a portion of the benzene from theterpolymer. Under these conditions, the benzene-terpolymer mixture ispassed to stripper 23 by means of line 24. Benzene is removed overheadby means of line 25, while a terpolymer product is withdrawn by means ofline 26. Under certain conditions, the dialauryl fumarate may beintroduced by means of line 18 and the vinyl acetate from zone 11. Also,the dilauryl fumarate may be introduced directly into zone 1 from zone30 by means of pump 31 and line 32.

The quantities mentioned above may be varied under certain conditions.For example, based upon 1,000 parts by weight of benzene, the amount ofvinyl acetate may be varied from about 100 to 250 parts by weight, andthe dilauryl fumarate and ethylene added in concentrations specifiedheretofore based upon the amount of vinyl acetate utilized.

The pour depressants of the instant invention are found compatible withother additive materials and may be blended successfully with petroleumoils containing minor amounts of viscosity index improvers, rustinhibitors, oiliness agents, oxidation inhibitors, and the like.

EXAMPLE 1 In order to further illustrate the invention, a number ofoperations were conducted in accordance with the above describedtechnique. The results of these operations are illustrated in Table Iwherein it is seen that the terpolymers of the instant invention arevery efiective pour point depressants.

TABLE I.TERPOLYME RS OF ETHYLENE-VINYL ACE- TATE-DILAU RYL FUMARATE POURDEPRESSANTS FOR MIDDLE DISTILLATE GAS OILS [Conditions of syntensis:about 1,400 ml. of benzene as solvent, ethylene pressure to maintain 900p.s.i.g., temperature 275 F. hours reaction nne Conditions A B C D EVinyl acetate, g 200 200 200 200 200 Injection period, hours 4 4 4Dilauryl iumarate, g. 52. 5 105 105 105 105 Injection period, hours. 4 43 Di-t-butyl peroxide, g 11. 9 11. 9 11. 9 11. 9 11. 9 Injection period,hours 4 4 5 5 4 Poul? depressing potency At 0.015 wt. percent 75 so 7570 70 At 0.025 wt. percent 85 85 85 80 90 1 Over 2 hrs.

2 At start.

3 Over 3 hrs., after vinyl acetate.

4 Cryoseopically in phenanthrene.

In reference oil, 50/50 blend of virgin and cracked gas oils, ASTM pour+25 F. Boiling range 350 to 625 F.

It is not intended that this invention be limited to the specificexamples presented by way of illustration. The scope of the invention islimited only by the appended claims.

What is claimed is:

1. A terpolymer of about 30 to 85 wt. percent ethylene,

about 10 to 40 wt. percent of an olefinically unsaturated C -C aliphaticmonoester selected from the group consisting of vinyl acetate, vinylpropionate and methyl methacrylate, and about 5 to 30 wt. percent of Cto C dialkyl ester of C ethylene dicarboxylic acid; said terpolymerhaving a molecular weight in the range of from about 1,000 to 4,000.

2. Terpolymer as defined by claim 1, wherein said olefinicallyunsaturated C -C ester is vinyl acetate.

3. Terpolymer as defined by claim 1, wherein said ethylene dicarboxylicacid is fumaric acid.

4. Terpolymer as defined by claim 1, wherein the amount of ethylene isabout to wt. percent, the amount of said C -C monoester is about 20 toabout 30 wt. percent, and wherein the amount of said C to C dialkylester of C ethylene dicarboxylic acid-is about 10 to 20 Wt. percent.

5. Terpolymer as defined by claim 1, wherein said C -C monoester isvinyl acetate, said ethylene dicarboxylic acid is fumaric and saidmolecular weight is about 1,500 to 3,000.

References Cited UNITED STATES PATENTS 2,480,551 8/1949 Cofi'man et al.260-785 2,570,788 1-0/ 1951 Giammaria 260485 2,721,877 10/ 1955 Popkinet a1 260485 3,215,657 11/1965 Beresniewicz et a1. 260-80.-8l

LORRAINE A. WEINBERGER, Primary Examiner E. J. SK'ELLY, AssistantExaminer

